A large number of different ambient sensors in motor vehicle applications are known from the prior art. These are seeing increasingly widespread use on account of the many and diverse new opportunities that such sensor systems provide in connection with driver assistance systems. The ambient sensors used in this case are radar sensors, camera sensors and lidar sensors, for example. Similarly, navigation systems, which are usually of GPS-based design, are also already present as standard in an increasing number of current vehicles. These navigation systems perform position finding on the basis of received satellite signals and guide the driver to the destination along a journey route determined using a digital map. By contrast, what are not yet ready for large-scale production are what are known as vehicle-to-X communication systems, the extensive introduction of which, at least for new vehicles, has already been decided upon for the years to come, however, and which are currently still subject to standardization efforts. These communication systems communicate wirelessly in this context and interchange data about information captured by ambient and vehicle sensors, inter alia, with one another.
In this connection, DE 10 2007 058 192 A1, which is incorporated by reference, describes a central controller for a plurality of assistance systems provided in a motor vehicle, at least some of which are equipped with ambient sensors, wherein, according to DE 10 2007 058 192 A1, which is incorporated by reference, a telematic system is also understood to mean an ambient sensor. The central controller is connected to the individual assistance systems at data level and plausibilizes the information from individual ambient sensors using the information from other ambient sensors. By way of example, the image information for a camera can confirm the distance measurement by a radar sensor. Individual pieces of sensor information can therefore be confirmed and are available in redundant form. Such coupling of individual signals from different sensors is also known as sensor fusion.
DE 10 2008 061 304 A1, which is incorporated by reference, discloses a vehicle-to-X communication device for a vehicle for wirelessly transmitting vehicle-relevant data. In this case, these data are transmitted to surrounding vehicles or to infrastructure devices. The communication device described comprises two separate communication units, the first communication unit being designed on the basis of a WLAN connection and the second communication unit being designed on the basis of a remote keyless entry (RKE) connection.
DE 10 2009 045 748 A1, which is incorporated by reference, discloses a method and an apparatus for ascertaining the status of wireless vehicle-to-X communication by a vehicle with its surroundings. To this end, not only is the transmission quality of received messages rated but also a statement about the quantity or quality of the communication subscribers is made. By way of example, this is accomplished by virtue of the analysis of the radio messages prompting ascertainment of the transit time for the message. In order to ascertain this transit time, each radio message may have a time stamp from a shared time base about its transmission instant, the shared time base being the time base from a global satellite navigation system, such as GPS or Galileo.
However, even when the time base from a global satellite navigation system is used as a shared time base, the vehicle-to-X communication systems known from the prior art are disadvantageous insofar as the different satellite navigation reception modules have different processing periods and processing methods for the satellite signals received, depending on the manufacturer. Therefore, even vehicle-to-X messages sent at the same time can be denoted using different time stamps. By way of example, one and the same time stamp can denote both that instant at which all satellite signals required for a position finding step are received and that instant at which the processing of all satellite signals is complete. Accordingly, the time discrepancy for identical time stamps may typically be several 100 ms. At a vehicle speed of approximately 100 km/h, a time discrepancy of 100 ms already results in a position error of 3 m, which is inadequate, particularly for safety-critical vehicle applications.